Message-Id: <3.0.6.32.20000211080749.00801100@mail.xtalwind.net>
Date: Fri, 11 Feb 2000 08:07:49 -0500
To: Lancair.list@olsusa.com
From: Judy <jandb@xtalwind.net>
Subject: Engine Mount and Sun and Fun
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I had my 320 project at Lakeland Sun and Fun last year in the composite
work area.  We had great fun and I plan to have it there again this year.
  
I had planned a standard IO320 engine installation.  However, Mario
Marsotte had developed a new gear box which I kept hearing about from
people who had seen it in the engine workshop.  Mario approached me the
last night of the show, we both worked till after midnight each night. We
discussed the value of the workshop process to homebuilders.  We also
discussed pros and cons of certified engines versus automotive engines.  We
decided if I could get help with the firewall forward installation I would
consider an Automotive engine.

Thus;  I spent a week at Oshkosh looking at engines and making plans.  I
purchased a Subaru engine from Crossflow Aero.  They have a Web site;
Crossflow.com.   Owned and operated by Jorge Alonso and his father.  One of
the many qualities I was looking for was a company that was willing to
install the engine at Sun and Fun for training purposes.  Jorge is willing.

I need some help on the engine mount.  The main question I have is how long
should the engine mount be?  Before you think we know nothing.  It’s I who
knows nothing not Jorge.  However, with all this talk about long mount Vs
short mount, I have an opportunity to move the CG.  I think I have confused
Jorge.  Jorge has all the data about his center of mass and many other
terms I am not familiar with.  Can anyone give us some information about
how far forward of the firewall the center of mass should be?  That may be
the question.

Presently we are scheduled to be in the composite workshop and engine
workshop with Forums on Sunday and Wednesday.  At least the first forum
will discuss how to inspect the engine when it arrives and unpacking.  Then
Jorge will demonstrate and so forth.  I am not sure what Jorge has planned
for his talks.  I hope it will be in a lesson plan format. Sounds exciting.

I have several other airframe tasks planned such as balancing the ailerons.
 Joe (Poly Fiber) said he would demonstrate some finish work but I need to
confirm this.    Sounds exciting.  I can use all the help I can get.  So if
anyone would like to participate while in Lakeland, please do.

Bobby Pate


[Bobby, I'm not sure that knowing the center of mass of the engine will do 
you much good given the fact that the addition of a PSRU and prop will
move it forward considerably.  I assume that the engine's CG in a typical
installation is somewhere between 22 and 26" forward of the firewall,
depending on engine accessories used and the prop that's  hung on the front.
As you might remember from a recent discussion here about CG issues, the
weight and location of individual components has little to do with your
actual W&B calculations, everything is determined by the weights taken at
each of the landing gear when the airplane is in the ready-to-fly 
configuration.  Granted, we need to be thinking about those individual weights
during the building process to insure that our CG envelope works out
favorably after everything is installed.  And now that the factory has moved
the forward limit to 11% MAC we can think about moving some things forward
that we couldn't before.  But that's a whole 'nuther discussion.

When I built the engine mount for my Mazda 13B Turbo I first ascertained the 
overall length of the PSRU and the location of the face of the prop flange
in front of the block.  LNC2's setup with typical Lycoming installations
with a short mount typically have the face of the prop flange about 36.5"
forward of the firewall.  Those with a long mount have the prop flange
located about 39" forward.  The standard cowling that came with my kit
(which included a long mount when purchased) had enough material at its
aft end for me to get out to that 39" forward-of-firewall prop flange face
with a few inches to spare for trimming.  Armed with that piece of data
and the length of my PSRU I built my mount so the flange would come out
at 39".  I imagine if you pass this information along to Jorge he will
be able to formulate a gameplan for your presentation.  Good luck, I'm looking
forward to seeing it.

  <Marv>                ]

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